If you plan to implement an optimization, I recommend a pointer propagation. This is very simple and still lots of optimizers ignore it. For example,
mem += 3;
while (mem[0]) { mem += 1; mem[0] -= 1; mem += 1; }
mem -= 4;
mem[0] = 0;
while (mem[3]) { mem[1] -= 1; mem += 2; }
mem[-1] = 0;
mem -= 1; /* you can safely ignore this at the end of file */
++++++++++[>++++++++<-]>--. N
-----. I
------. C
++. E
<++++++[>------<-]>. !Shame on me for using Visual Studio. I turned to pure Linux/Mac development environments in recent years.
Then try and see if it's faster than this one - http://mazonka.com/brainf/bff4.c
See BrainF.cpp in particular.
It's a decent first illustration of the great level of abstraction LLVM offers.